CVE-2026-64108
Estado: AnalizadaAlta (7.8)—
In the Linux kernel, the following vulnerability has been resolved:
cifs: Fix busy dentry used after unmounting
Since commit 340cea84f691c ("cifs: open files should not hold ref on superblock"), cifs file only holds the dentry ref_cnt, the cifs file close work(cfile->deferred) could be executed after unmounting, which will trigger a warning in generic_shutdown_super: BUG: Dentry 00000000a14a6845{i=c,n=file} still in use (1) [unmount of cifs cifs]
The detailed processs is: process A process B kworker fd = open(PATH) vfs_open file->__f_path = *path // dentry->d_lockref.count = 1 cifs_open cifs_new_fileinfo cfile->dentry = dget(dentry) // dentry->d_lockref.count = 2 close(fd) __fput cifs_close queue_delayed_work(deferredclose_wq, cfile->deferred) dput(dentry) // dentry->d_lockref.count = 1 smb2_deferred_work_close _cifsFileInfo_put list_del(&cifs_file->flist) umount cleanup_mnt deactivate_super cifs_kill_sb cifs_close_all_deferred_files_sb cifs_close_all_deferred_files // cannot find cfile, skip _cifsFileInfo_put kill_anon_super generic_shutdown_super shrink_dcache_for_umount umount_check WARN ! // dentry->d_lockref.count = 1 cifsFileInfo_put_final dput(cifs_file->dentry) // dentry->d_lockref.count = 0
Leer descripción completaMostrar menos
Fix it by flushing 'deferredclose_wq' before calling kill_anon_super.
Fetch a reproducer in https://bugzilla.kernel.org/show_bug.cgi?id=221548.
CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 7.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.18%
- Percentil entre todas las CVEs puntuadas: 6
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation75 % - Impacto principal
T1499.004Application or System Exploitationimpact70 %
Vulnerabilidad de escalada local en kernel Linux (AV:L, PR:L) que causa condición de carrera en dentry/dput, resultando en DoS por exhaustión de recursos (uso después de liberación de memoria).
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
CWE
- NVD-CWE-noinfo
Referencias
- https://git.kernel.org/stable/c/5e7d9d0805e58fa3760894e73115b7a74024fd07
- https://git.kernel.org/stable/c/bdc349a87f1fb02c18c4071858a06542bfea783d
- https://git.kernel.org/stable/c/c68337442f03953237a94577beb468ab2662a851
- https://git.kernel.org/stable/c/c7364cea52531534676b9f7dbc0a477c11f4c050
- https://git.kernel.org/stable/c/e1ffa6cf662383f95816eed1b623429d82675e75
- https://git.kernel.org/stable/c/f2deaa2f409a4598eaa10f2a93a676c0632af248
JSON original (NVD)
Mostrar
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: Fix busy dentry used after unmounting\n\nSince commit 340cea84f691c (\"cifs: open files should not hold ref on\nsuperblock\"), cifs file only holds the dentry ref_cnt, the cifs file\nclose work(cfile->deferred) could be executed after unmounting, which\nwill trigger a warning in generic_shutdown_super:\n BUG: Dentry 00000000a14a6845{i=c,n=file} still in use (1) [unmount of\n cifs cifs]\n\nThe detailed processs is:\n process A process B kworker\n fd = open(PATH)\n vfs_open\n file->__f_path = *path // dentry->d_lockref.count = 1\n cifs_open\n cifs_new_fileinfo\n cfile->dentry = dget(dentry) // dentry->d_lockref.count = 2\n close(fd)\n __fput\n cifs_close\n queue_delayed_work(deferredclose_wq, cfile->deferred)\n dput(dentry) // dentry->d_lockref.count = 1\n\t\t\t smb2_deferred_work_close\n\t\t\t\t\t _cifsFileInfo_put\n\t\t\t\t\t list_del(&cifs_file->flist)\n umount\n\t\t cleanup_mnt\n\t\t deactivate_super\n\t\t cifs_kill_sb\n\t\t cifs_close_all_deferred_files_sb\n\t\t\t cifs_close_all_deferred_files\n\t\t\t // cannot find cfile, skip _cifsFileInfo_put\n\t\t\tkill_anon_super\n\t\t\t generic_shutdown_super\n\t\t\t shrink_dcache_for_umount\n\t\t\t umount_check\n\t\t\t WARN ! // dentry->d_lockref.count = 1\n\t\t\t\t\t cifsFileInfo_put_final\n\t\t\t\t\t dput(cifs_file->dentry)\n\t\t // dentry->d_lockref.count = 0\n\nFix it by flushing 'deferredclose_wq' before calling kill_anon_super.\n\nFetch a reproducer in https://bugzilla.kernel.org/show_bug.cgi?id=221548."
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